Content caching at the terminal user device (UD) utilizing the device to device (D2D) communications is a promising technology to enhance the performance of mobile networks in terms of latency, throughput, energy consumption and so on. In this paper, a novel method of content delivery using multiple devices to single device (MDSD) communications through D2D links is presented. In this method, the Zipf distribution with exponent shape parameter is adopted to model the content caching popularity which affects the achievable signal to interference plus noise ratio (SINR). In order to investigate the advantage of the proposed MDSD method, firstly, a closed-form expression of the outage probability is theoretically derived for a single D2D communication to evaluate the success of content delivery to the UD. Secondly, the expression of the outage probability for MDSD communication is derived, where the outage probability is modeled as a function of content caching popularity, the density of UDs, and the size of cooperative area. The research work is further extended to address the frequency reuse among different UDs in one cell, where a frequency band factor is introduced, and the optimal radius of the cooperative area is defined and analysed. The analytical results are validated by the simulation results and show that the outage probability decreases drastically when the popularity of the content increases, or the radius of the cooperative area increases. Using the derived closed-form expression of the outage probability, the area spectral efficiency (ASE) of the system is presented. Furthermore, the results show that as the frequency band factor increases, the outage probability decreases. Finally, it is shown that the MDSD outperforms the single D2D-based method.
Multipath environment is a limitation fact in optimized usage of wireless networks. Using smart antenna and beamforming algorithms contributed to that subscribers get a higher-gain signal and better directivity as well as reduce the consumed power for users and the mobile base stations by adjusting the appropriate weights for each element in the antenna array that leads to reducing interference and directing the main beam to wanted user. In this paper, the performance of three of beamforming algorithms in multipath environment in terms of Directivity and side lobe level reduction has been studied and compared, which are least mean square (LMS), genetic algorithm (GA) and grey wolf optimization (GWO) technique. The simulation result appears that LMS algorithm aids us to get the best directivity followed by the GWO, and we may get most sidelobe level reduction by using the GA algorithm, followed by LMS algorithm in second rank.
These days long term evaluation (LTE) is considered the common mobile technology around the world and there is a need to maximize the network performance to satisfy the increased demand in terms of the cell capacity and coverage. These are many parameters in the network configuration and in the surrounded environment, which have great effects on the network performance. Examples of parameters are the system overhead rations, the required capacity of the network, neighbor cell load, and link budget parameters. The determination of the optimum configuration parameters, which achieve the best network performance, is a main step in the planning process in addition to it is continuous step in network optimization phase. In this study, the effects of some parameters will be investigating to get the best parameters that achieve the best network performance in terms of capacity of the cells and coverage area. The study will start by discussing introduction about LTE network components and protocols, and then the main parameters of the protocols will be revising. The study will display the results of changing many parameters related to LTE protocols and surrounding environment parameters on the LTE network performance.
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